Thin Diffractive Optical Elements for Wide Field-of-View VR

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Solution Overview

Problem

Current virtual reality (VR) devices are limited by cost and manufacturing constraints to achieve wide field-of-view (FOV) while maintaining a thin and lightweight design, as conventional optics are bulky and expensive to produce.

Innovation Solution

The use of thin diffractive optical elements (DOEs) with stair-like profiles, fabricated using a stack of thin films with different etch selectivities, allows for the creation of high-numerical aperture lenses that provide wider FOVs without increasing the thickness and weight of VR devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional optics are used to achieve wide field-of-view, then FOV is improved, but device thickness and weight increase

Engineering Contradiction:

Improvefield-of-viewVSAvoiddevice weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent applies diffractive optical elements that are only a few micrometers thick, replacing conventional bulky lenses. These thin film-based DOEs achieve wide FOV (80-110 degrees) while maintaining minimal thickness, directly resolving the contradiction between FOV and device weight/thickness.

Inventive Principle:

Principle #30Flexible shells and thin films

2Adaptability or versatility

If conventional optics are used to achieve wide field-of-view, then FOV is improved, but manufacturing cost increases

Engineering Contradiction:

Improvefield-of-viewVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent changes the optical parameter approach from conventional refraction-based lenses to diffraction-based elements. This parameter change enables mass fabrication using semiconductor manufacturing techniques, significantly reducing manufacturing cost while achieving wide FOV.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces mechanical lens systems with diffractive optical elements that can be fabricated using thin-film deposition and lithography processes, substituting complex mechanical optical systems with planar, easily manufacturable structures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Length of moving object

If thin diffractive optical elements are used, then device thickness is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improveoptical element thicknessVSAvoidfabrication precision

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent uses master templates or masks that define the diffractive pattern, allowing precise replication of the optical element structure. This copying approach ensures consistent manufacturing precision across mass production while maintaining thin profile.

Inventive Principle:

Principle #26Copying

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables VR devices to achieve FOVs of over 80° with reduced bulkiness and cost, compared to conventional optics, while maintaining high optical efficiency and precision.

Implementation Method 1

diffractive optical elements (DOEs) with stair-like profiles, fabricated using a stack of thin films

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS10845609B2Diffractive optical elements for wide field-of-view virtual reality devices and methods of manufacturing the same

Publication Date: 2020.11.24 TAHOE RES LTD

AI summary

Diffractive optical elements for wide field-of-view virtual reality devices and methods of manufacturing the same are disclosed. An example apparatus includes a substrate and a thin film stack including alternating layers of a first material and a second material. The thin film stack defines an annular protrusion. The annular protrusion has a stair-like profile. Top surfaces of separate ones of steps in the stair-like profile correspond to top surfaces of separate ones of the layers of the second material.